1. Technical Field
The present invention relates to a manufacturing method for an electrooptic device, an electrooptic device, and an electronic device. More specifically, it relates to a manufacturing method for an electrooptic device having a color filter, and the construction of the same.
2. Related Art
As is known in the art, liquid crystal displays, which are a kind of electrooptic device, generally include a transmissive liquid crystal display, which performs a transmissive display by using transmitted light emitted by illumination means such as a backlight, and a reflective liquid crystal display, which has a reflector plate reflecting external light and which performs a reflective display by using reflected light of the external light. The transmissive liquid crystal display provides a relatively bright display, but its illumination means such as a backlight requires large power consumption. This raises a problem in that, when the transmissive liquid crystal display is used for a portable electronic device such as a mobile phone, its operating time is short since the battery capacity is limited. Another problem with the transmissive liquid crystal is that its display is difficult to view while outdoors during the daytime. On the other hand, the reflective liquid crystal display requires no illumination means, but the reflective liquid crystal display does not always provide sufficient brightness for display because it makes use of external light. Therefore, the reflective liquid crystal display particularly involves a problem in that it is deficient in color reproducibility for color display and viewability in a dark place.
In view of such situations, a transflective liquid crystal display capable of switching between the transmissive display and reflective display in accordance with environmental circumstances, has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 2002-229010 (page. 5, FIG. 3)). This type of liquid crystal display has a transflective layer constituting a reflecting section that reflects external light for each pixel, and a transmitting section formed by an opening in a reflecting film. In this case, when illumination means is turned on, the illumination light passes through the transmitting section of the transflective layer to thereby implement a transmissive display, while, when the illumination means is turned off, external light is reflected by the reflecting section of the transflective layer to thereby implement a reflective display.
In order to realize a color display in the above-described transflective liquid crystal display, a color filter is provided on the observation side of the above-described reflecting layer (i.e., on the incident side of the external light).
In the above-described conventional transflective liquid crystal display with a color filter, in the transmissive display, the illumination light passing through the transmitting section in each pixel passes through the color filter only once, whereas in the reflective display, the reflective light formed by external light being reflected by the reflecting section in each pixel passes through the color filter twice during one round trip. This unfavorably causes a large difference in the color reproducibility between the transmissive display and reflective display.
As a possible structure for solving the above-described problem, there is a structure in which an opening that is two-dimensionally superimposed on a part of the reflecting section is provided in the colored layer of the color filter. For example, as shown in FIG. 12, there is provided a transflective layer 11 by forming an opening 11a in the reflecting film, and a transmitting section 10PT and a reflecting section 10PR are constituted of the transflective layer 11. In each pixel 10P, an opening 12a is provided in a colored layer 12 of the color filter, and a part of the reflecting section 10PR of the transflective layer 11 is exposed on the incident side of external light. This allows the chromaticity of the reflective display to be adjusted independently of that of the transmissive display, by varying the opening area of the opening 12a. 
In order to form the above-described structure, a patterning method shown in FIG. 14 is used. First, as shown in FIG. 14(a), a reflective material such as aluminum is deposited on the surface of a transparent substrate 10 such as glass substrate, and as shown in FIG. 14(b), a transflective layer 11 having an opening 11a therein is formed by patterning. Next, as shown in FIG. 14(c), a colored layer 12 comprising a photosensitive resist is applied over the transflective layer 11. Then, as shown in FIG. 14(d), this colored layer 12 is selectively exposed by using a mask 13 formed into a mask pattern having a light-shielding section 13a, and thereby, as shown in FIG. 14(e), an opening 12a is formed in the colored layer 12.
In this case, however, the opening 12a of the colored layer 12 is a part of the pixel 10P and an opening having an area as minute as about several micrometers to a dozen or so micrometers square, and therefore, it is difficult to accurately control the shape of the opening 12a in the above-described photolithographic process to achieve high reproducibility regarding the opening area. Specifically, as shown in FIG. 13, for example, when exposure is performed using a mask with a rectangular light-shielding section 13a for forming a rectangular opening in a negative-type colored layer, if a desired opening area is very small, the vicinity of the corners of the opening is susceptible to exposure due to diffracted light or the like during an exposure operation, as compared with the other portions thereof. As a result, the colored layer is apt to remain in the vicinity of the corners of the opening 12a during the development operation. This makes it difficult to achieve high reproducibility regarding the opening area. Also, for the reflective display, in the opening 12a, light does not pass through the colored layer at all, whereas in the area other than the opening, light passes therethrough twice in a round trip. A slight change in the opening area of the opening 12a would widely vary the chromaticity of the reflective display. This method, therefore, involves a problem in that the color reproducibility of the reflective display cannot be achieved due to variations in the opening area of the opening 12a. 
Accordingly, one object of the present invention is to solve the above-described problems, and to provide a method for manufacturing a transflective electrooptic device and its structure capable of adjusting the chromaticity of the reflective display, and of improving the reproducibility of the adjusted reflective display.